Interpretive Summary: The primary concern of global change has centered on the rapid increase in atmospheric concentrations of primary greenhouse gases [carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O)] since the Industrial Revolution in the latter part of the 19th century. A “state of the state” report on global change in rangelands and pasturelands indicates that three significant advances have been made regarding plant and soil responses to increasing atmospheric CO2 and land management practices to mitigate global change. First, elevated CO2 levels can significantly impact rangeland plant community dynamics, increase water use efficiency and reduce nitrogen content of the plant material. Second, land management practices, such as grazing, fertilization, fire, and introduction of legumes and improved grass species can increase soil organic carbon storage in rangelands and pasturelands. Third, the development of non-interference methods offers promise to monitor methane emission from isolated animals to large feedlots.

Technical Abstract:
Primary questions covered in this review of global change on rangelands and pasturelands were: 1) what is known regarding the influence of increasing atmospheric CO2 on rangeland and pastureland soils and plant communities, and 2) how land management practices on rangelands and pasturelands might mitigate global change through the Greenhouse gas Reduction through Agricultural Carbon Enhancement network (GRACEnet) proposed scenarios. A “state of the state” report on global change in rangelands and pasturelands indicates that several significant advances have been made regarding plant and soil responses to increasing atmospheric CO2 and land management practices to mitigate global change. First, elevated CO2 levels can significantly impact rangeland plant community dynamics, increase water use efficiency and reduce nitrogen content of the plant material. Whether these plant community shifts and plant responses to single, large increases in CO2 reflect what happens as continuous and incremental increases in CO2 occur over decades remains unknown because plants and soil microorganisms possess the ability to genetically adapt to rising CO2. Second, land management practices, such as grazing, fertilization, fire, and introduction of legumes and improved grass species can increase soil organic carbon storage in rangelands and pasturelands. Third, the development of non-interference methods offers promise to monitor methane emission from isolated animals to large feedlots. Our knowledge of how trace gas emissions (N2O and CH4) are affected by increasing atmospheric CO2 and land management practices is still growing and available data are still too limited to extrapolate to large landscape situations with certainty. [GraceNet related].